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Conformational Analysis of [3.3]Paracyclophane
Author(s) -
Sako Katsuya,
Meno Tatsuya,
Shinmyozu Teruo,
Inazu Takahiko,
Takemura Hiroyuki
Publication year - 1990
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19901230334
Subject(s) - conformational isomerism , chemistry , cyclohexane conformation , cyclophane , crystallography , stereochemistry , crystal structure , molecule , organic chemistry , hydrogen bond
According to a VT‐NMR study, [2,2,11,11‐D 4 ][3.3]paracyclophane ( 1‐D 4 ) exists as a mixture of chair and boat conformers in the ratio of 1.0: 1.3 (ΔG o = 0.1 kcal/mol) at ‐70°C with an energy barrier for the chair‐boat inversion of 12.0 kcal/mol (270 MHz, ca. 1% CD 2 Cl 2 solution, T c = ‐ 15°C). The conformer ratio (chair/boat) is dependent on the concentration of 1‐D 4 ; it is 1:1 in ca. 1% CD 2 Cl 2 solution but 1:2 in ca. 5% CD 2 Cl 2 solution, due to preferential crystallization of the chair conformer.